Sensitized sheets for screen reflectography



July 8) T952` L. P. F. VAN DER GRINTEN Erm. 2,502,741

' SENSITIZED SHEETS FOR SCREEN REFLECTOGRAPHY Filed Ooi;` 24, 1946 fig-5.

INVENTORS I ooawmn P. F'.

VAN DER GRINTEN MARINUS f. VALLEN BY @reen-JLM ATTQRv EVS Patentecl July 8, 1952 y I Applicatin october 24, 1946, serial No. 705,309

In the Netherlands November 1, 1945 nolaims. (CL95-s) k `lThis-'invention relates to; improveA ents in senscreen pattern must be closely adjacent to and sitiz'ed sheetsfor making screen reflex copiesfrom iirmly held in contact with the sensitized film originals which are opaque Aor;vsIIbStantially and 'must remain attached until after the exopaque to light rays orffrom originals printed on posure, during' which exposure the film has a both-sides. 1 l f y y :i 5 tendency to stick .to the glass panel over which yTo prepare thesetso called screen'reflex `copies the lmis moving-in conventional exposure -apon sensitized transparent iilm,l Athe light frays paratus and (2) after the exposure has been .must',when'acting on'the'sensitizedlayer,beisplit effected the screen pattern must be fquickly,

up-'by p'assagef`through a screen cf. applicants easily and completely separable from `the sensipriorV invention ldescribed in'U. S. Patent No. 10 tized lm, preferably without thief-'necessity of 2,026,292) This division of the light must satisfy soaking in a bath. vrThe diiculty inthe producspecial requirements. Contrary to those of halftion of a successfullm 'of this character is'evitone' screen production, in which division' i'sf're-` dent from the opposing requirements which must quired with graded diierences of intensity, the be reconciled.

division in screen-reilectographymethods vinust The known screened sensitized sheets, of which be such' that only vsharp 'transitions from full to' the screenpattern organically belongs to. the

minimum intensity occur." Y K Y sensitized film-hardly satisiies these two require- This particular division is,` in practice, obments.v 1 s tained byimaking thelight pass through a screen .i The screened sensitized sheen-according to the close to the sensitized layer, i. e. through a coverpresentinvention, rin order to satisfy these two ing screen 'having exclusively sharp transitions, requirements, vcomprises a screen (screen .patthe screen being Ain as close contact with the sentern) which is organically (or in other words: sitized layer aspossible. The immediate proxconstitutionally or structurally) united Withafilm' imity' of :the screen "and-the sensitized layer'is hereafter termed the skin, itself connected tothe necessary, ybecause in practice diius'ed light is 25 sensitized hn by adhesion. This ensures that mostly-use'dor the radiation.v the screen pattern is in as close contact as posf The screen and the sensitized layer must not, sible with', i. e. in the immediate vicinity of the during exposure, move in relation to each other, sensitized layer o'f the lm, although the screen more particularly not when the exposure takes pattern is organically united with the'skin and place 'ini'an"exposing-apparatus in which the 30 will remain so. riginalfto-be copied.' is carried over a paneto- This screened sheet has the advantage of, getlir withthe senstiveniaterial by vmeans of firstly, that it satises the main requirement in aconveying cloth. f r thelpractice of reiiectography, viz., close contact U. Patent No. '2,026,292 describes sensitized and rm connection between screen-pattern and sheets for. .screen relectography, which themsensitized layer and, secondly, that it is easy to selves contain a 'covering screen, the screen being operate, is not easily injuredy and can hence stand organically connected with thev sensitized film. up to packing and shipment `and exposure par- Wi'th some. of .these screened sensitized sheets the ticularly exposure by transport. through an exscreenimay remain on the nlm after the exposure, posing apparatuswith frictional resistance. Furwith others vit has t'o be'removed after exposure, 40 thermore vthe removal of the screen can readily as otherwise -the screen pattern would make.' the be effected by breaking the adhesion and by rereex copy useless. moving theskin carrying the screen, which makes Example 2 of the said U. S.' patent describes long soaking and the use of `cleaning materials the production of a screen reflex copy by means and suchlike unnecessary. of suchA a screened sensitized sheet, in which the 45 The present invention further contemplates a screen is removed after exposure. A cellulose form of screened sensitized sheet in which the film is there sensitized with a diazo compound on screen skin can be stripped oiT dry from the senwhich a screen pattern is printed with a certain sitized lm. The skin can then be so tough that ink preparation, and this preparation is soaked, it is possible to tear or lift it entirely from the after copying, in an alkaline developing bath and lm after exposure, either byv hand or by other PATENT oFFIcE if necessary removed'by rubbing, means, breaking the adhesion, by which it is This invention is concerned with a sensitized connected to the sensitized nlm. sheet for screen-.reflectography provided with a 'This form of sheet with a screen skin capable-of removable screen. The two main obstacles in being stripped o'i dry isspecally advantageous preparing products of this kind are (l) the wherevthe sensitized layer'requires, for its finishthe diazotype, which are developed with amrnonia vapour.

There are particular advantages in the combination of a screen skin with a sensitized film sensitized with a diazo-compound. Herewith it often occurs that towards the end of the exposure the adhesion connecting skin andfilm weakens, so that the screen skin is nowI looser than prior to the exposure;Y and .thisihelps in re- If in this case the skin has a local Nscreen'less.

sensitized sheet 1, suitable for the purpose and provided with a screen skin is passed with the skin side'directed downwards between the cylinders I and 2, itwill unite with the .adhesive paper at the point of passage between the said cylinders and together therewith proceed on'its way to the edge 8 of frame 3. Here the adhesive paper makes a sharp angle downwards, while the sensitized sheet .runs straight on (as a rule it is stiff enough to do that). If its degree of adhesion with respect to the sensitized sheet is smaller than 'that with respect to the adhesive layer, the-screenskin will now be carried along area, in other words is locally entirely pervious to light, so that the film sensitized with -diazocompound is thus entirely exposed in this area to a sudden intensive radiation, the skin will in this area be loosened still more, so that the re moval of the skin may be started at this point.Y It goes without saying thatthe screerrless area' will by preference be chosen at an edge ofthe sheet. The diminution of Vthe adhesion by ex` posure Yis probably due to the development of nitrogen. Y s

It is also possible according to a further feature of the invention to providev screened sensitized sheets having the screen skin loose from the sensitized film in some place or other, for preference at an edge or corner of the sheet, so that the removal may be started with this loose piece.l

:According to a special embodimentyof the invention, the removal of the skin can be effected particularly satisfactorily by closely contacting the sensitized sheet on its screened ,side with an adhesive surface and thereafter `separating the two surfaces again. In this case the adhesive surface must be of rsuch a nature' that the adhesion'of the skin with respect to the .sensitized sheet is smaller than that with respect to the adhesive surface. i It is often easier to effect the removal of the skinin this way than by stripping off the screen skin manually. This is particularly 'the case when the screen skins are very thin and weak, and it applies particularly to skins 'weighing less than approximately .20 g./m.2. 1 This embodiment for the removal of the screen will, in many cases, make `it possible to remove the screenA mechanically. This will beelucidated with reference to the drawing, in which Fig. 1 is an enlarged diagrammatic rcross-section through a screen'skin sheet made according to one embodiment of this invention, while Figs..2 andY 3 diagrammatica'lly represent devices adapted to effect -the removal of the screen mechanically.

In Fig.` 2, I is a cylinder on whicha cylinder 2 exercises a slight pressure. 3 is a frame parallel to the cylinder I and extending over its entire length.y 4 is a roll of adhesive paper. When the apparatus is in operation, the adhesive paper 5 will move in the direction of the arrows from roll 4 by way of cylinder I and frame 3 to roll 6, where it is re-rclled. The cylinder I is actuated, for vinstance by hand, by means of a crank, the roll 6 being driven in advance run by means of friction, whilst the roll 4 is'checked. The atihesive paper 5 consequently runs through the apparatus under tension. On the cylinder I it has its adhesive layer outermost. When a `on the latter; inthis manner the screen is removed from the sensitized sheet. After that, it can `be subjected to the usual after-treatment, for example in Vthe case of a diazotype sheet, a half-wet or dry developing process. 'Ihe descreening apparatus can be coupled with a developing-apparatus.

In Figf, Sis a stationary hollow cylinder'with the Vpartition I0, landthe slots II and I2, extendingeven theentire length of the cylinder. On one-sideof the partition I0 there is the chamber I3 and on 'the other side the chamber I4. These chambers are closed at one end, the other end being connected vto an air-pump, pumping the air from I3 to I4. The air consequentlystreams in at I;I yandfout again at I2. Round this cylinder 9 a perforated -cylinder I5 rotates inthe direction of the arrow. The cylinder 2 exerts pressure on I5. The outer surface of I5 may be adhesive. After an image has been formed, a screened Vsensitized sheet 'I with. the screen skin directed downwardsis introduced between cylinder-2 and cylinder I5,- moves .inthe direction of the arrow, is caught by lthe suction at VII and stuck on the surface of I5, after whichjit is lightly `loosened at I8 by means of a pointed -or narrow knife-shaped object I6` and conducted fartherY (e. g. by hand) in the direction of the arrow. If at I8 the adhesion `of the screen skin with respect to the wall I5-which adhesion .is due to the suck-ingrand/or adhesive power of the said wallis greater than that with respect to the sensitized sheet,l the'screen skin will con-- tinue its way ltogether with the wall -I5 and is llzown oir by the air-stream coming from the slot It will be understood that in, this description of the drawing words like adhesive surface and the like, are to be taken in a wide sense. Thus, the conception adhesive surface" erg. also implies a so-.called vacuum surface .or a combination of a vacuum and an 'adhesive surface.

In practice the sensitized surface of the sensitized ilrn is sometimes made .dull (mat). ',While this improves the 'copy which is made, as it becomes easierv to read .and can be written on, lsuch duliing however, has this disadvantage, that' `it di'fiuses and obstructs the light falling through the screen openings during exposure.

It was found that this objection of the dulled sensitized films is eliminated when they are provided with a screen skin, according to this invention. The adhesive between skin and sensitized film neutralises dulling, vand yetgitreappears when, after the exposure,` the skin together with theadhesive is removed.

When the sensitized nlm partly or entirely loses its absorbing power by exposure, the screened sheet according .to the inventionmay, by a preliminary exposure of the screened side of it. be made more sensitive.

The Screened sheets according to the invention are handy and clean in us-while thecopies pro`` duced by means of themfare not disfigured'by particles of screen remaining behind, which often occurs in practice with the known type screened sheets where the screen pattern is organically B. A skin of acetyl-cellulose of 35 g. per mfis I unilaterally saponied and sensitized with' a solutionof:v.-'. 6 g. p-diazo-o-chlorodimethyl-analine-chloride 2 g. oxalic acid 1' g. phenol 20 g. ethylalcohol 8.0 gwater I A relief covering screen is made in the following way.

Small elevations 'in the form of squares are produced on a glass plate by etching it, the sides of these squares being approximately 0.035 mm. and the height approximately 0.015 mm., .While the fdistance from centre to. centre of these squares is approximately 0.08 mm. The relief side of the plate is then covered by a thin silver layer and thereafter polished; due to the latter operation the mirrorlike silver layer onlyremains in the depths of the relief and disappears on the elevations, so that the squares in relief become transparent (compare U. S. Patent 2,295,632).

A relief covering screen thus obtained is copied iny contact, by means of are light, on the above described sensitized skin B, in such a Way that vthe sensitized areas lying beneath the parts pervious to light of the covering screen are bleached. The skin is then developed in ammonia vapour. The screened skin B thus obtained is on its screen side provided with-.a thin layer of rubber latex and then dried. The screen skin is then attached under considerable pressure on its 4latex side, to the sensitized side of `the lrn A sensitized with p-diazoethylbenzyl-aniline.

The component parts of a screen skin sheet structure so obtained are illustrated diagrammatically in the magnified cross-section of Fig. 1, wherein Athe associated legends indicate the nature of components. In'thisgUre, 20 is a flexiblev base film transparent to light to which the covering positive printing diazo layer l2Iyis sensitive diazo layer and consists olea-'myriad of .minute lintegral areas 24 opaque to said light and interpersed with minute integral areas 25 which are transparent to said light. The adhesive lm 22 forms a flexible junction between theA screen skin and the sensitized base lmpermittingvthe screen skin to be stripped 01T so astoyield the -base lm as a screenless exposure.

By means of the sensitized screened sheet thus obtained'it is possible by exposure through `the screen to make a reex copy, e. g. in an exposing apparatus provided with' frictiona'l` Asheetieeding means. The exposure is nolonger than if 4the sensitizedlm had not been drilled. After v Vapour.

Vexposure theescreen skintogether with the layer of adhesive is loosened at one corner and the Whole is stripped from thevfilm, whereafter the sensitized sheet is developed by applying to ita thin layer of a diazotype-developerl alkalized with soda, containing an azo-component ei g.' phlo'ro-l glucinol.' The screen reflex-copy obtained-"is superficially dull and canbe written-on. If the screened sensitized vsheet is` subjected,Vv before making the reflex-copy, to a preliminary exposure through the screen-pattern, e. Hg. with a dark background, then the time of exposure in makingthe reflex-copy can be shortened. y

y Example 2 Y v, l The same procedure is followed as in Example 1," but the film A is sensitizedin the usual Way with an aqueous solution of l 5% p-diazodimethylmaa-tomieinesmpnateiy l2%v oxalic acid 1 thiourea Y 1 phloroglucinol 0.1% rgelatine 10% ethyl alcohol -After exposure the screen skin- ,134 is stripped off and the sheet is developed in ammonia vapour.

, Example 3 A.- An acetyl-cellulose lm with a Weight of g. per m? is unilaterally saponified and on that side sensitized with an aqueous solution of:

B.,A skin of acetyl-cellulose of l5 g. per 111.2, affixed to smooth paper, is saponied on-its free side and on that side sensitized with an aqueous solution of: Y e

6% p-diazoochlorodimethyl-aniline-chloride 2% oxalic acid f 1% phenol 20% ethyl alcohol' A relief covering screen such as described in Example' 1, is copied in contact byjrneansV of aro light on. the above-mentioned sensitized skin, after which the latter is developed in ammonia- The screen skin, by' means'ofadilute solution of rubber in benzene, is made to adhere with the screen side tothe sensitized side of the film A. Thereupon the'paper on which the skin B wasattached, is'stripped 01T. f v A The sheet consisting of the parts Aand B 'is subjected to exposure in the manner customary inscreenereectography, after.` which, in 'anapparatusl according to Fig. 2, itv is brought into contact on vits screen side with an "adhesive paper obtained by treating paper With a, solution of:

said sheetk comprising a flexible base carrying over on one side alight sensitive pStive printing diazo laye'rglsaid base being transpare V'to light to which said-layer is sensitivegfand an'laid-Hering but separable skin having as an organically united rpart thereof a. screen pattern in substantially face to face relation to the sensitized layer of the base and consisting of a myriad of interspersed minute areasA respectively transparent and opaque-to such light, without intermediate gradated transitions, which method comprises moving a separate surface into contact with the screen skinfadhering the exposed surface of the skin to said separate surface with strength greater than the strength of adhesion of the skin tothe base, and then forcing the base and said separate surface through divergent paths so that the screen skin separates from the base with said separate surface.

2. VA sensitized diazotype sheet .for screen reilectographycomprisin'g, as aunitary flexible sheet structure, a flexiblefbase iilm sensitized over one side with a positive-printing diazo layer and transparent to the light to which said `layer is sensitive, and a relatively thin iiexible skin overlying the sensitized side and joined firmly thereto over substantially the whole surface thereof so that the base lm and skin do not separate in handling or exposing the sheet, said skin comprising an integral light screenwhich at least nearly contacts the light-sensitive layer and consists of a myriad of minute areas opaque to said light interspersed with minute areas transparent thereto without intermediate gradated transitions, the junction between the skin and the base -iilmbeing frangible so 'that the skin is strippable to yield rthe base iilm as a screenless exposure.

3. A sensitized diazotype sheet for screen reectography comprising, as a unitary flexible sheet structure, a flexible cellulosic base lm carrying a positive-printing diazo layer over one side and transparent to the light to which said layer is sensitive, and a relatively thin flexible cellulosic skin overlying said sensitized side and joined firmly thereto over substantially thewhole surface thereof so that the base film and skin do not separate in handlingV or exposing the sheet, said skin comprising an integral lightA screen which at least nearly contacts the light-sensitive layer and consists of a myriad ofminute areas opaque to .said light interspersed `with minute areas transparent thereto without intermediate gradated transitions, the junction between the skin and the base film being frangible so that thek skin .is strippablev to yield the base film as a screenless exposure.

A sensitized diazotype sheet jfor screen reiiectography comprising, as a unitary iiexible sheet structure, a iexible baserlm carrying a positive-printing diazo layerfover one side and transparent to the light to which said layer ,is sensitive, anda relatively thin flexible skin overlying said sensitized side and joined firmlythereto over substantially the whole surface thereof so that the base film `and skin do not separate in handling or exposing the sheet, said skin comprising an integral light screen vwhich at least nearly contacts the light-sensitive layer'and consists of a myriad of minute areas opaque to said light interspersed with minute areas transparent sheet, structure, a flexible base film carrying a positive-printing diazo layer over one side and transparent to .the lighty to which said layer `is sensitive, and a relatively thin exible skin overlying said sensitized side and joined firmly thereto over substantially the Whole surfacewthereof so that the base film and skin do not separate in handling or exposing the sheet, said skin comprising an integral light screen which at least nearly contacts the light-sensitive lay-er and consists of a myriad vof minute areas opaque to said light interspersed with minute areas transparent thereto without intermediate gradated transitions, the weight of said skin being less than about 20 grams per square meter of surface area, the junction between the skin and the base Yfilm being frangible so that the skin is strippable to yield the base film as a screenless exposure.

6. A sensitized diazotype sheet for screen reectography comprising, as a unitarygexible sheet structure, a exible base iilm carrying a positive-printing diazo layer over one side and transparent to the light to which said layei` is sensitive, and a relatively thin exible skin overlying said sensitized side and joined firmly thereto over substantially the whole surface thereof soy that Ythe vbase lm and skin do not separate in handling or exposing the sheet, said skin comprising an'integralv light Ascreen which at least nearly contacts the light-sensitive layer and consists 'of a myriad of minute areas opaque to said light interspersed with minute areas transparent thereto without intermediate Vgradated transitions, the junction between the skin and the base vlm being frangible and the skin having a greater cohesive strength than its strength of adhesion to the base film so that the skin is strippable bodily from the base lm in a' dry state.

7. A sensitized diazotype sheet for screen reflectography comprising, as a unitary iiexible sheet structure, a flexible base film carrying a positive-printing diazo layer over one sideand transparent to the light to which saidlayer is sensitive, said layer containing a light-sensitive diazo compound and an azo coupling component, and a relatively thin iiexible skin overlying said sensitized side and joined firmly thereto over substantially the whole surface thereof so that the base film `and skin do not separate in handling or exposing the sheet, said skin comprising an integral light screen which at least nearly contacts'the light-sensitive layer vand consists of a myriad of minute areas opaque to saidY light interspersed with minute areas transparent thereto Without intermediate gradated transitions, the junction between the skin and the base film being frangible so that the skin is strippable to yield the base film as a screenless exposure.

8. A sensitized diazotype. sheet for screen re- Vflectography comprising, as a unitary flexible sheet structure, a flexible base lm carrying a positive-printing diazo layer over oneA side and transparent to the light to which said layer is sensitiveyand a relatively thin flexible skin overlying said sensitized side andjoined firmly thereto over substantially the whole surface thereof so that the base lm and skin do not separate in handling or exposing the sheet, said skin comprising` an integral light screen which' at least nearlycontacts the light-sensitive layer and consists of fa myriad' of minute areas opaque tosaid light ,interspersed with minute areas transparent thereto .:without 1 intermediate `gradated transitions, said skin havingA at least one screenless local portion at a margin of the sheet, and the junction between the skin and the base film being frangible so that the skin is strippable to yield the base film as a screenless exposure.

9. A sensitized diazotype sheet for screen reflectography comprising, as a unitary flexible sheet structure, a exible base film carrying a positive-printing diazo layer over one side and transparent to the light to which said layer is sensitive, and a relatively thin flexible skin overlying said sensitized side and joined firmly thereto over substantially the whole surface thereof so that the base film and skin donot separate in handling or exposing the sheet, said skin comprising an integral light screen which at least nearly contacts the light-sensitive layer and consists of a myriad of minute areas opaque to said light interspersed with minute areas transparent thereto without intermediate gradated transitions, the junction between the skin and the base film being frangible so that the skin is strippable to yield the base film as a screenless exposure, the sensitized side of the base film being roughened to give the exposure a mat finish.

10. A sensitized diazotype sheet for screen refiectography comprising, as a unitary flexible sheet structure, a flexible base film carrying a `positive-printing diazo layer over one side and transparent to the light to which said layer is sensitive, and a relatively thin fiexibie skin overlying said sensitized side and joined firmly thereto over substantially the whole surface thereof so that the base film and skin do not separate in handling or exposing the sheet, said skin comprising an integral light screen which at least nearly contacts the light-sensitive layer and consists of a myriad of minute areas opaque to said light interspersed with minute areas transparent thereto without intermediate gradated transitions, the junction between the skin and the base lm being effected by a thin film of a flexible pressure-sensitive adhesive transparent to said light and being frangible so that the skin is stripfiectography comprising, as a unitary flexible sheet structure, a iiexible base film carrying a positive-printing diazo layer over one side and transparent to the light to which said layer is sensitive, and a relatively thin flexible skin overlying said sensitized side and joined firmly thereto over substantially the whole surface thereof so that the basey film and skin do not separate in handling or exposing the sheet, said skin comprising an integral iight screen which at least nearly contacts the light-sensitive layer and consists of a myriad of minute areas opaque to said light interspersed with minute areas transparent thereto without intermediate gradated transitions, said screen being a photographic formation in a diazotype layer on one side of said skin. the junction between the skin and the base film being frangible so that the skin is strippable to yield the base film as a screenless exposure.

LODEWIJK PIETER FRANS VAN DER GRINTEN. MATHEUS MARINUS PAULUS VALLEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

2. A SENSITIZED DIAZOTYPE SHEET FOR SCREEN REFLECTOGRAPHY COMPRISING, AS A UNITARY FLEXIBLE SHEET STRUCTURE, A FLEXIBLE BASE FILM SENSITIZED OVER ONE SIDE WITH A POSITIVE-PRINTING DIAZO LAYER AND TRANSPARENT TO THE LIGHT TO WHICH SAID LAYER IS SENSITIVE, AND A RELATIVELY THIN FLIXIBLE SKIN OVERLYING THE SENSITIZED SIDE AND JOINED FIRMLY THERETO OVER SUBSTANTIALLY THE WHOLE SURFACE THEREOF SO THAT THE BASE FILM AND SKIN DO NOT SEPARATE IN HANDLING OR EXPOSING THE SHEET, SAID SKIN COMPRISING AN INTEGRAL LIGHT- ACREEN WHICH AT LEAST NEARLY CONTACTS THE LIGHT-SENSITIVE LAYER AND CONSISTIS OF A MYRIAD OF MINUTE AREAS OPAQUE TO SAID LIGHT INTERSPERSED WITH MINUTE AREAS TRANSPARENT THERETO WITHOUT INTERMEDIATE GRADATED TRANSITIONS, THE JUNCTION BETWEEN THE SKIN AND THE BASE FILM BEING FRANGIBLE SO THAT THE SKIN IS STRIPPABLE TO YIELD THE BASE FILM AS A SCREENLESS EXPOSURE. 